Perhaps, Apple has lined up some publishers to announce a library worth of iBooks created (or re-created) using iBooks Author - many more than previously announced. Perhaps, it will be the contents that will make this launch compelling and justify the price (to the customer).

I'm not sure about all the "layers" of the display, but I can tell you categorically that the cost of neither the battery nor the case scales up linearly with size as you described. That might seem to be the intuitive relationship if you consider only raw components. But there is a process cost as well. For example, 4 iPhone back plates will cost more than an iPad back plate, assuming the latter is indeed 4 times the size of the former (which it isn't). More generally,...